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		<h1>Common Functions</h1>

		<p>CodeIgniter uses a few functions for its operation that are
			globally defined, and are available to you at any point. These do not
			require loading any libraries or helpers.</p>

		<h2>
			is_php('
			<var>version_number</var>
			')
		</h2>

		<p>
			is_php() determines of the PHP version being used is greater than the
			supplied
			<var>version_number</var>
			.
		</p>

		<code>
			if (is_php('5.3.0'))<br /> {<br /> &nbsp;&nbsp;&nbsp;&nbsp;$str =
			quoted_printable_encode($str);<br /> }
		</code>

		<p>
			Returns boolean
			<kbd>TRUE</kbd>
			if the installed version of PHP is equal to or greater than the
			supplied version number. Returns
			<kbd>FALSE</kbd>
			if the installed version of PHP is lower than the supplied version
			number.
		</p>


		<h2>
			is_really_writable('
			<var>path/to/file</var>
			')
		</h2>

		<p>is_writable() returns TRUE on Windows servers when you really
			can't write to the file as the OS reports to PHP as FALSE only if the
			read-only attribute is marked. This function determines if a file is
			actually writable by attempting to write to it first. Generally only
			recommended on platforms where this information may be unreliable.</p>

		<code>
			if (is_really_writable('file.txt'))<br /> {<br />
			&nbsp;&nbsp;&nbsp;&nbsp;echo &quot;I could write to this if I wanted
			to&quot;;<br /> }<br /> else<br /> {<br />
			&nbsp;&nbsp;&nbsp;&nbsp;echo &quot;File is not writable&quot;;<br />
			}
		</code>

		<h2>
			config_item('
			<var>item_key</var>
			')
		</h2>
		<p>
			The <a href="../libraries/config.html">Config library</a> is the
			preferred way of accessing configuration information, however
			config_item() can be used to retrieve single keys. See Config library
			documentation for more information.
		</p>

		<h2>
			show_error('
			<var>message</var>
			'), show_404('
			<var>page</var>
			'), log_message('
			<var>level</var>
			', '
			<samp>message</samp>
			')
		</h2>
		<p>
			These are each outlined on the <a href="errors.html">Error
				Handling</a> page.
		</p>

		<h2>
			set_status_header(
			<var>code</var>
			, '
			<var>text</var>
			');
		</h2>

		<p>Permits you to manually set a server status header. Example:</p>

		<code>
			set_status_header(401);<br /> // Sets the header as: Unauthorized
		</code>

		<p>
			<a href="http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html">See
				here</a> for a full list of headers.
		</p>


		<h2>
			remove_invisible_characters(
			<var>$str</var>
			)
		</h2>
		<p>This function prevents inserting null characters between ascii
			characters, like Java\0script.</p>


		<h2>
			html_escape(
			<var>$mixed</var>
			)
		</h2>
		<p>This function provides short cut for htmlspecialchars()
			function. It accepts string and array. To prevent Cross Site
			Scripting (XSS), it is very useful.</p>

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